Pressure responsive electric switch



July 4, 1933. R w G V 1,916,427

PRESSURE RESPONSIVE ELECTRIC SWITCH Filed Sept. 5, 1931.

- Patented July f4, 1933 I 1 U D STATES PATENT OFFICE FRIEDRICH WILHELM KbRVEB, OF DUISBURG, GERMANY, ASSIGNORTO HYDRAULIK GESELLSCHAF'I. MIT BESUHRANKTER HAFTUNG, OF DIJ'ISBURG, GERMANY PRESSURE RESPONSIVE ELECTRIC SWITCH Application filed September 5, 1931, Serial No. 561,426, and in Germany May 21, 1929.

This invention relates to a pressure responsive electric switch, and particularly to such a switch for use in conjunction with and-comprising as component parts thereof elements of a compressed air accumulator. The invention is described hereinafter as employed for use in controlling electrical circuits governing accumulator control means, but may also beused for controlling indicating circuits, such as for indicating high and low water levels, etc. As such circuits may be of various types, and as conventional circuits may be used, none are herein shown, as the same are unnecessary to a complete understanding of my invention.

Compressed air accumulators without piston or float are known in which the accumulator is provided with axial movement and is at the same time acted on by a counterweight. The condition of the accumulator at any given moment is determined by the difference in weight between the accumulator with, the

liquid therein and the counterweight. If the latter weight is the greater, the accumulator moves up, but if the opposite is the case it falls. These two movements are utilized for arresting the inflow of water and opening the inlet and preventing the withdrawal of water.

This construction may be employed for accumulators having small water capacity, but it is not suitable for accumulators of largercapacity.

- For this reason the large accumulators are generally housed in a piston or float, their movements, caused by the changing depth of water in the accumulators, inducing the inflow of water and arresting it and closing the discharge valve. v

In practice these devices give rise to difliculties, as the driving force acting on the piston 0r float does not ensure that the valve will make its movements at the right moment, as when the movement transmitting members are fouled.

According to the invention an accumulator is provided which dispenses with both piston and float while retaining its stationary character. To secure this'result a device is provided operating as a contact barometer and connected to the accumulator, the control liquid (mercury), which is affected by the rising and falling column of water in the accumulator closing contacts at various heights by means of contact fingers extending to different depths in the mercury chamber whereby when'the lowermost level of the water in the accumulator is reached the water discharge valve closes and when the levelof the water is at its highest the pump is disconnected from the accumulator.

A construction of apparatus according to the invention is illustrated in the accompanying diagrammatic drawing, which shows apparatus according to the invention in sectional elevation. In the drawing, compressed air under the desired pressure is passed through the pipe 2 to the accumulator 1, which holds water under pressure, and it fills the space 3 above the suri of the water. Water enters the water spac by way of the pipe 4, through which it can be drawn off. This pipe is provided with a control valve 6.

A pipe 17 leads from the water space 5 to a chamber 8, which contains in its lower part 9 the control liquid which advantageously is specifically heavier than water.

This liquid is employed to efiect direct control, that is, without the aid of a float. The chamber 8 is provided to communicate with the chamber 18, while the pipe 11 connects the chamber 8 with the air space 3 in the accumulator; The heavier liquid (mercury) in the lower part 9 of the chamber 8 is under the pressure of the water in the upper part of the chamber 8. As the chamber 18 is in communication with the space 3 by means of the pipe 11, balance of pressures is secured and thus the weight of the water is the only operating force. Contact fingers extend to different depths in the chamber 18 and as the column of mercury 19 therein rises the tips of the contact fingers are covered by the mercury one after the other. Thus circuits 13, 14, 15 are closed and actuate valves not shown in the drawing.

It is assumed that the control liquid closes the circuit 15. By'this means a valve in the Water discharge pipe is held open. If the I has at first no efi'ect upon the valve that connects the pump with the accumulator. The pump is disconnected from the accumulator only when the circuit 16 is'closed. The con nection is restored only when the circuit 14 is broken. By this means when the level of the water is low changes in level in the accumulator fail to connect and disconnect the pump with every change of level.

\Vhen the liquid rises from the lowest level the valve in the discharge pipe should not open until contact of the mercury with the contact finger 15 is made.

It will be understood that the manner in which the circuits 13, 14, 15 and 15 are caused to effect the control of the entry and discharge of water from the accumulator may be efi'ected by any suitable known means operating mechanically, hydraulically or electrically under electrical control. Thus, they may be used to effect the control of the valve 6 or with a plurality of such valves and to eflect the disconnection of the pump from the accumulator when required, such disconnection being also effected by means of a suitably controlled valve or like element.

I claim:

1. In a receptacle for holding a column of water, a reservoir containing air at a pressure greater than atmospheric pressure, for holding water and air under pressure, means for supplying water to and discharging the water from said receptacle, the said receptacle having an air space above the column of water therein communicating with said reservoir, a holder in open communication with and containing a movable column of aerate water supplied from and under the pressure of the body of water in the receptacle and also containing a movable column of mercury in contact with and subjected on one side to the pressure of the water column, a connection between the reservoir and the holder for supplying air to the receptacle and maintaining the column of mercury therein under air pressure counteracting the air pressure on the column of water in the receptacle, whereby the column of mercury is made responsive to variations in the weight of and adapted to rise and fall with the body of the water in the receptacle, and electric circult contactors terminating at difl'erent levels and adapted to be engaged by the mercury on the rise and fall of the latter.

2. In a pressure responsive electric switch, a receptacle normally containing water and air under pressure, means for admltting water to and discharging it from the receptacle, a source of air under pressure communicating with the receptacle for placing the water therein under a predetermined pressure greater than atmospheric pressure, a pair of chambers containing a conducting fluid and in communication at their bottom portions for the back and forth flow of the fluid between them, a connection between one of said chambers and the water containing space of the receptacle for the flow of water from the receptacle to the chamber above the level of and resting upon the body of conducting fluid in said chamber, a connection between the said source of air under pressure and the other chamber for subjecting the conducting fluid therein to a pressure opposed to the air pressure on the water in the receptacle and first-named chamber, whereby variations in the level of the body of water in the receptacle cause responsive variations in the level of the conducting fluid in the secend-named chamber, and electrical switching means of which said fluid forms a part and including contactors extending to different degrees down into the second-named chamher for make and break contact with the fluid at difi'erent levels for governing suitable indicating or controlling circuits.

FRIEDRICH WILHELM KURVER. 

